In U.S. application Ser. No. 527,535 filed Aug. 29, 1983 and Ser. No. 527,536 filed Aug. 29, 1983 are disclosed compositions comprising a solid metal oxide substrate having niobium (V) or tantalum (V) halide(s)/oxide(s) bound to the surface of the substrate. These compositions are used as catalysts in hydrocarbon reactions. When these materials come into contact with oxygen or compounds containing oxygen which is weakly covalently bonded to the compound, they have their activity as catalysts decreased. The instant process provides a method by which these oxygen-deactivated catalysts are regenerated to higher activities.